FORT LAUDERDALE, Fla., March 10 -- Over the past few weeks of spring training, Baltimore Orioles right-hander Randor Bierd has created a buzz with a supposed mystery pitch that he's used during an impressive string of relief outings. Teammates and coaches alike have debated the exact nature of the pitch that blends the deceiving arm action of a change-up with the sudden sink of a split-fingered fastball.

"It's actually very impressive," said catcher Chris Heintz, who has caught Bierd this spring.

Said pitching coach Rick Kranitz, "It looks like a fastball coming out and it's a little different."

Whatever it is, Bierd has used the pitch effectively enough to jump into the thick of what has evolved into a highly competitive battle for a spot in the Orioles' bullpen.

"I think I can help the bullpen, I hope to get a chance to help," Bierd said. "I've got a very nasty pitch."

Though the Orioles will be without relievers Danys B¿ez and Chris Ray as they recover from elbow ligament replacement surgery, the wide-open battle could be for two spots at most.

Meantime, several pitchers have been enjoying success during camp, making the competition deep.

"They're fighting for what they want and that's good," Kranitz said.

Manager Dave Trembley said he intends to carry 12 pitchers on the 25-man roster, leaving seven in the bullpen.

Left-hander George Sherrill, acquired in the Erik Bedard trade, is on track to win the team's closer's job. Meantime, Trembley said right-hander Dennis Sarfate has a spot to lose. Sarfate, acquired in the Miguel Tejada trade, is helped by the fact that he has no minor league options remaining.

Meantime, veteran setup men Chad Bradford and Jamie Walker will be expected to reprise their roles this season. At least one bullpen opening will be occupied by a long reliever, which will likely be one of the several pitchers competing for a starter's job, thus leaving two open spots. But Trembley said he could carry two long men, which would leave only one opening for another reliever.

"There's a lot of competition," Kranitz said. "They're throwing the ball well and they're making it a tough decision, which is what you'd hope would happen. We're going to take the best guys we have. They're competing a lot and that's what I'm looking for."

Six Orioles relievers have yet to allow an earned run during spring training.

"They're playing like it's their last day and that's the way you should," Walker said. "It's definitely encouraging knowing that we'll have a little more depth this year."

In four one-inning outings, former Arizona Diamondbacks closer Greg Aquino has allowed one base runner. Former Chicago White Sox reliever Ryan Bukvich has allowed three hits in three appearances.

Meantime, Bierd has emerged as one of the most intriguing candidates for a bullpen slot.

"He's got a little deception which helps and hitters don't take good swings off him," Kranitz said. "I think he's an interesting guy, no question. He's come in and for a guy who's just played in Double-A, he's got some moxie about him."

Bierd, Baltimore's choice in the Rule 5 draft, hasn't allowed a run in three appearances since surrendering two runs in his first spring outing on Feb. 29.

"Randor Bierd has been a very pleasant surprise," Trembley said. "He has a swing and miss pitch for a young guy, he's come in some situations that he's thrown strikes, shown very good focus. He's got a little deceptiveness in his arm action."

On Monday, he worked out of trouble against the Los Angeles Dodgers with a pair of strikeouts. One came on his so-called mystery pitch; he maintains it is simply a very good change-up with movement.